Senate GOP plan to delay corporate tax cut shows the move that matters most to investors isn’t a sure thing

Congressional Republicans and President Donald Trump are confident they will notch a win on taxes. Investors may not see the final result as the win they had anticipated.

A hint of this came Thursday, when the Senate Republican proposal to rewrite the tax code included some big differences with the House plan released earlier this month. One that stuck in the stock market’s craw was a proposal to delay cutting the corporate tax rate until 2019, versus a 2018 start under the House proposal. That means no bump in earnings next...